Can PHP GD Determine the Similarity of Two Images?

The question under consideration inquires if it's possible to ascertain if two images are identical using PHP GD by comparing their differences. This entails acquiring the difference between the two images and determining if it comprises entirely of white (or any uniform color).

According to the provided answer, hashing functions, as suggested by other responses, are not applicable in this context. The comparison must pertain to the image content rather than the files themselves.

Utilizing PHP Extensions for Image Comparison

In PHP, two popular extensions for image manipulation are ImageMagick and GD. ImageMagick provides a range of tools that can be leveraged for this purpose through the PHP ImageMagick extension.

ImageMagick: A Powerful Tool for Image Comparison

ImageMagick's compareimages() function is designed specifically for comparing images. However, the PHP extension's documentation leaves much to be desired, necessitating some trial and error in usage. The function's behavior is further elaborated in the ImageMagick documentation.